Influenza, commonly known as “the flu”, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae, the influenza viruses.
Influenza viruses lead to perilous infections in humans. Aside of the known human influenza viruses there are numerous influenza viruses in animals with the potential to infect humans such as swine flu viruses or avian flu viruses. The immune system can prevent the infection by the generation of neutralizing antibodies, however due to their high mutation rate and high variability in their surface hemaggalutinin molecules influenza viruses can escape from the recognition by antibodies. Mutations in viral genes and reassorting of viral genes in infected cells are the major driving forces for the development of new influenza epidemics.
Aside of antibodies, cytotoxic T-cells (CTL) play an important role in the control of influenza viruses. Although they cannot prevent the infection of a cell, they are crucial to the control of infection by the elimination of virus infected cells. Influenza-specific CD8+ T-cells recognize by their T-cell receptor usually 8 to 10 amino acid long peptides which are generated from viral proteins by cellular proteasomes within the cytoplasm of infected cells. After binding to HLA class I-molecules, the peptide/HLA-complexes are transported to the cell surface for presentation to CD8+ cytotoxic T-cells (CTL). The binding of the specific T-cell receptor of the CTL with the HLA-I/peptide-complex, leads to activation of the CTL with subsequent lysis of the infected cell by the CTL.
The T-cell receptor of the HLA-class I-restricted CD8+CTL consists of two proteins, the TCR alpha chain and the TCR-beta-chain. Both the TCR-alpha-chain and the TCR-beta-chain are formed from various gene segments, which are rearranged from a variety of variable gene segments at the TCR-alpha locus and the TCR-beta locus. The TCR-alpha chain consists of a variable (V) gene segment, a J (Joining) gene segment and a constant (C) gene segment. The TCR-beta chain consists of a variable (V) gene segment, a J (Joining) gene segment, a D (diversity) gene segment and a constant (C) gene segment.
The individual TCR of individual T-cells is generated during the thymocyte development by recombination of gene segments. D-to-J recombination occurs first in the β chain of the TCR. This process can involve either the joining of the Dβ1 gene segment to one of six Jβ1 segments or the joining of the Dβ2 gene segment to one of seven Jβ2 segments. DJ recombination is followed (as above) with Vβ-to-DβJβ rearrangements. All gene segments between the Vβ-Dβ-Jβ gene segments in the newly forming complex are deleted and the primary transcript is synthesized that incorporates the constant domain gene (Vβ-Dβ-Jβ-Cβ). mRNA transcription splices out any intervening sequence and allows translation of the full length protein for the TCR Cβ chain.
The rearrangement of the alpha (α) chain of the TCR follows β chain rearrangement, and resembles V-to-J rearrangement described for Ig light chains (see above). The diversity of the somatically rearranged TCRs is enhanced further by the introduction of additional nucleotides between the V and J gene segments of rearranged TCR-alpha genes. The rearrangement of TCR gene segments provide a diverse repertoire of approximately 1018 different TCRs. The TCR-alpha-chain and the TCR-beta-chain pair after their synthesis to yield the αβ-TCR-heterodimer that is expressed on a majority of T cells.
The specificity of the recognition of the viral peptides is mainly determined by the CDR3-region of both the TCR-alpha and the TCR-beta chains. Each CTL usually expresses only a single functional T-cell receptor (TCR) that allows the recognition of only a single antigenic peptide. Dependent on the individual TCR sequence, TCRs can exhibit a certain cross-reactivity that may allow also the recognition of peptide variants to a certain degree.
In the prior art influenza-specific T-cell receptors (TCR) are known (Berdien et al., 2013). Verna et al. (2004) describe tumor growth inhibition by hTER-transduced T cells. Thereby, they describe CTLs which specifically recognize the influenza matrix protein 58-66 (GILGFVFTL) on HLA-A2-positive cells.
Viral matrix proteins are structural proteins linking the viral envelope with the virus core. They play a crucial role in virus assembly, and interact with the RNP complex as well as with the viral membrane. They are found in Morbillivirus, Paramyxovirus, Orthomyxovirus and Pneumovirus. The M1 protein of the influenza virus is a viral matrix protein, showing affinity to the glycoproteins inserted in the host cell membrane on one side and affinity for the RNP complex molecules on the other side, which allows formation at the membrane of a complex made of the viral ribonucleoprotein at the inner side indirectly connected to the viral glycoproteins protruding from the membrane. This assembly complex will now bud out of the cell as new mature viruses. Viral matrix proteins, like many other viral proteins may exert different functions during the course of the infection.
US 2006/0155115 A1 describes synthetic multivalent T-cell receptor complexes for binding to a MHC-peptide complex, which multivalent TCR complex comprises a plurality of TCRs specific for the MHC-peptide complex. The TCRs are refolded recombinant soluble TCRs. One of the TCRs described is specific for the epitope58-66 of the influenza matrix protein in HLA-A2.
WO 2012/038055 A1 describes tumor antigen-specific TCRs and T-cell epitopes. The TCRs which are directed against the human tumor antigen TPTE were cloned from CD4+ T cells, which recognize peptides with HLA-2.
WO 2008/039818 A2 describes a modified TCR. WO 2007/131092 A2 discloses chimeric TCRs which are tumor-specific.
There is a need in the art for improved means and methods for detecting, preventing and/or treating influenza, in particular via influenza-antigen specific cells or by immunotherapy.